The genus is typified by its green coloration, the wings being rather
densely scaled. The venation of the forewing is typical, and the hindwing
lacks humeral veins. The forewing has single post- and antemedial fasciae
of darker green between which is a dark discal dot. The hindwing has a
single fascia, and both wings have an irregular row of submarginal flecks.
The fringes are usually darkened. The females are much larger than the
males, the wing markings more diffuse and often of different
configurations, so that 'marriages' are often difficult. The arrangement
of the submarginal flecks is more constant between the sexes than the
other markings and hence is often useful for matching them.

The male antennae are broadly bipectinate throughout, those of the females
much more narrowly so.

The male genitalia have a tegumen like an arched strap, on the posterior
edge of which are dentate processes (referred to as the uncus by Roepke)
that often provide diagnostic features. The valve is divided into upper
and lower setose processes, reflecting the structure of the apical process
of the aedeagus (the suboral projection of Roepke). There is no cubile. In
the illustrations of genitalia they have been separated at the junction of
tegumen and vinculum, and the whole ring has been flattened out.

The mature larva of T. vishnou has been described by Gardner (1941). It
has two anterolateral processes with black hair pencils on the prothorax
as in other
lasiocampids. The other thoracic segments lack transverse brushes or
patches. There are distinct verrucae, blue-black with a black margin and
with long, fine black setae. The rest of the upper surface of the body has
an extremely dense covering of fine shaggy grey hair. This is longer
laterally, and on the dorsum it peaks into thin white tufts that are a
little stronger anteriorly and posteriorly. The head and legs are reddish
marked with yellow.

Like most Oriental members of the family, the larvae have a wide range of
diet, being recorded from the following families and genera (Roepke;
Gardner; Sevastopulo, 1939; Pholboon, 1965; unpublished CIE records):

Barringtoniaceae:

Barringtonia.

Bischofiaceae:

Bischofia.

Combretaceae:

Combretum, Quisqualis, Terminalia.

Dipterocarpaceae:

Shorea.

Euphorbiaceae:

Aleurites, Ricinus

Fagaceae:

Quercus.

Geraniaceae:

Geranium.

Lauraceae:

Persea.

Leguminosae:

Butea.

Lythraceae:

Lagerstroemia.

Melastomataceae:

Melastoma.

Meliaceae:

Swietenia.

Myrtaceae

Eucalyptus, Eugenia, Melaleuca,
Psidium, Rhodomyrtus, Syzygium.

Polygonaceae:

Polygonum.

Punicaceae:

Punica.

Rhamnaceae:

Ziziphus.

Rosaceae:

Rosa, Rubus.

Sapindaceae:

Schleichera.

Sonneratiaceae:

Sonneratia.

The
larvae are often found semi-gregariously. Pupation is in a dark brown,
saddle-shaped cocoon, felted with the hairs of the larva; it is attached
to a twig or something similar (Roepke, 1951: 108).

The genus has by far its greatest diversity in Sundaland, being
represented in mainland Asia mainly by T. vishnou; there are six species in
the Philippines (Owada & Kishida, 1986), and one in Sulawesi; viridana
Joicey & Talbot, purported to be from New Guinea (represented by the
holotype male only) was undoubtedly mislabelled and is Sundanian

In Borneo the genus is most diverse in the lowlands but there are also a
number of exclusively montane species. The monotypic genus Crinocraspeda
Moore (N.E. Himalaya, China) is closely allied to Trabala.